Cryptography is the practice and study of logical means used to achieve information confidentiality, integrity and authenticity. It covers, among other things, encryption (making some data unreadable except for those who know a given secret element, called a key), data hashing (in particular for ...

learn more… | top users | synonyms

0
votes
1answer
28 views

How to verify the signature value in a SSL certificate?

According to RFC 3280 a certificate's basic syntax is Sequence := { tbsCertificate signatureAlgorithm signatureValue } In tbsCertificate, SubjectPublicKey is the public key of the ...
0
votes
1answer
375 views

Bitwise cipher Cryptography

I'm doing an online cryptography course. There is a question in which it is given that the encrypted text for; OwBPAAQXAE9UC0FVBQxODgZSCUUMAQwCCApYRBJZBR0LDhoAGApPHQAUAQNZRAJPGwQbDQBDDREKQA== Is ...
9
votes
2answers
3k views

Is it safe to use rng-tools on a virtual machine?

I am currently working on an app that needs to create GPG key pairs using the gpg tool. Unfortunately, this tool takes a long time to generate a key pair if there is insufficient entropy/randomness ...
7
votes
3answers
991 views

What are the disadvantages of using public key cryptography when encrypting files? [duplicate]

I am wanting to encrypt a file with my public key, my friend told me that this is not a good idea but did not explain why. Can someone explain please.
5
votes
2answers
961 views

Is HTML5 sessionStorage secure for temporarily storing a cryptographic key?

Assume I am building a local web application (e.g. browser extension) in HTML5 to encrypt a database locally. Access to the database is controlled by a password and a cryptographic master key is ...
0
votes
2answers
72 views

Is open source a good option for cryptography libraries? [closed]

I am trying to find good cryptography library to use with my project. I found open source options like openSSL and many more and also proprietory options like Intel Integrated Performance Primitives ...
0
votes
0answers
28 views

security authentication protocol [duplicate]

I'm "creating" a secure authentication protocol for my system and it is this: C-> S C S-> C N(once) C-> S Kc,aut[N] S-> AUT Ks,aut[C,Kc,aut[N]] AUT-> S Ks,aut[N] the line : X ...
-1
votes
0answers
29 views

Decrypt asymmetric private key with user password [closed]

I want to store sensitive information in database. My idea is I use RSA encryption I store public key in database and I would like to decrypt private key with user password and I also store this in ...
9
votes
5answers
2k views

Is this RSA/AES combination good?

The team of developers I am part of is trying to develop a safe way to exchange sensitive data between a server and mobile devices. We have come up with the following algorithm: Device generates ...
1
vote
1answer
262 views

Bypass SSL Certificate Pinning using SSL Vulnerablilities

I am wondering if it could be possible to sort of "bypass" the certificate pinning protection of Android or iOS using for example the POODLE SSL vulnerability. According to this blog Entry it is ...
0
votes
2answers
120 views

Why don't the majority of today's malware use strong cryptography?

While reading another story of botnet takedown, my wondering has reached its apogee: Why don't malware authors use cryptography (encryption + signing) provided by good libraries when their creations ...
0
votes
0answers
41 views

How does Signal Protocol, used by `whatsapp` Works?

I want to understand the process of The Signal Algorithm, I have google it, but unable to find any good Article or tutorial. I want to understand the basic definition and functionality of The signal ...
1
vote
1answer
78 views

AES step by step

I can't seem to find an AES tutorial that starts from Unicode to Cipher text. All of the tutorials I found starts with 128 bit block already. Also, where do I start or what topics do I have to start ...
9
votes
2answers
807 views

techniques to detect & mitigate Crypto-ransomware?

Crypto ransomware attacks are the latest concerns for our organization, we need to verify if we are adequately protected from them & if affected, what are the generic mitigation measure? How do ...
2
votes
2answers
134 views

number of ciphertext-plaintext pairs needed in double encryption

So I know in single encryption you would simply require at least 1 pair of plaintext-ciphertext, to carry out an exhaustive key search; you continue trying different keys until one is found that ...
1
vote
0answers
25 views

Create a signed file from the detached signature and the clear text file content

Assuming I have the following: data.txt data.ps7 (the detached signature) Can I generate the bundled signed file ? Any example would be great, using C#, Java or openssl or any other tool ?
4
votes
2answers
63 views

Signature that can only be verified by author and recipient - without pre-shared key

Desiderata: Alice wants to send a message to Bob for him to keep and to be able to refer to, such that Bob can be certain that the message came from Alice and was not tampered with. Alice also ...
1
vote
1answer
64 views

Cryptography behind RedHat subscription system (DRM)?

I have to do a project like a subscription manager. Ideally this should work like RedHat subscriptions. I'm having a hard time figuring out how it was implemented. How do they manage to avoid a ...
1
vote
1answer
48 views

Is the method of hardening the creation of a Cryptographically Generated Address (CGA) called hash extension

CGAs are sha1 hashes truncated to a 59 bit value. Along with a 3 bit security parameter they form a IPv6 address (more precisely the interface identifier). from wikipedia: The Sec parameter ...
116
votes
6answers
44k views

Password Hashing add salt + pepper or is salt enough?

Please Note: I'm aware that the proper method for secure password storage hashing is either scrypt or bcrypt. This question isn't for implementation in actual software, it's for my own understanding. ...
3
votes
1answer
86 views

What would be the repercussions in Information security, if someone found a way to factor large numbers quickly?

I am curious as to how exactly cyber-security would be affected if someone found a way to factor a large number quickly into its multiples. Let's assume that the time required for factorization is ...
46
votes
6answers
9k views

Is using a public-key for logging in to SSH any better than saving a password?

Using a public/private key pair is fairly convenient for logging in to frequented hosts, but if I'm using a key pair with no password, is that any safer (or less safe) than a password? The security ...
14
votes
3answers
79k views

CryptoWall 3 - how to prevent and how to decrypt?

My father's computer is now infected with CryptoWall 3, according to the link below. http://www.bleepingcomputer.com/virus-removal/cryptowall-ransomware-information#CryptoWall Is there a way to ...
4
votes
1answer
127 views

What are active research topics in SSL/TLS?

I don't know whether it is right to ask a question here for my MTech dissertation. I thought there is no good place in the world where I can find security experts like here. I am interested in doing ...
0
votes
1answer
53 views

How many hashes do I need to compute to get x collisions?

I know that you need to hash about 2^(N/2) to find a collision taking into account the birthday problem. But I'm not really sure about more than one collision, I mean, collisions with different ...
3
votes
0answers
242 views

How Does Telegram's Identity Verification Work?

Note: please refrain from commenting on Telegram's design of OTHER parts, as it will distract from the stem of the question. Background: Signal (Previously, "TextSecure" app) uses specific "Your ...
3
votes
1answer
64 views

Is having a unique key to encrypt data not sufficient

Is it necessary to use a unique Initialization Vector (IV) with various cipher modes of operation (e.g. CBC) even though I use a unique key to encrypt plain text every time? It is said that an IV ...
112
votes
7answers
21k views

Why shouldn't we roll our own?

Why shouldn't we create our own security schemes? I see a lot of questions around here about custom crypto and custom security mechanisms, especially around password hashing. With that in mind, I'm ...
6
votes
2answers
632 views

Requiring 2 keys to access a content

I need to use an external service that can only be accessed by password. I don't like the idea of storing the plaintext password on the server, but AFAIK there's not much I can do. Considering this ...
-1
votes
1answer
63 views

What defines a “good” cryptographic algorithm? [closed]

The title pretty much says it all. I am looking for a formal definition of what a good crypto algorithm is. I cannot find anything online.
1
vote
1answer
65 views

how is public key being exchanged in asymmetric cryptography?

I understand that exchanging public key between parties is challenging task in asymmetric cryptography.Can someone help me understand how it is achieved?
9
votes
1answer
173 views

How do EMV contactless cards protect against replay attacks?

I understand that standard RFID cards are vulnerable to replay attacks however, how do smart cards which are also contactless protect against replay attacks? Is this decided by the chip or by the ...
1
vote
1answer
60 views

Hide data from user, but process it in application

Is there a way to hide the data that's received somehow from the user? In particular, I have some data that gets send from a webserver to an application. I want the application to process the data, ...
2
votes
1answer
64 views

Can an attacker make in-app-purchases of my products in their app?

My iOS app needs to store a pre-shared secret. It cannot embedded within the App Bundle itself because it could be extracted by statically analysing the bundle. Apple's In-App-Purchase system allows ...
2
votes
1answer
56 views

Question on MAC(Message Authentication code)?

I am new to Cryptography and unable to understand clearly about MAC concept. As per MAC concept, Sender 'A' will encrypt the original message with symmetric key to create MAC1 value and then will send ...
3
votes
1answer
47 views

Is this good/secure method for client-server communication encryption?

Something came to my mind, and I wonder if this is proper method for client-server communication, and if this method is wide-used. On connection, client generates seed, encrypts it using asymmetric ...
4
votes
2answers
58 views

Does EMV protect against sniffing PAN data from untrusted network?

I have received conflicting information in regards to the security of PAN data on the wire. Can this be sniffed with properly configured EMV at an atm? To quote from the link below: ...
2
votes
2answers
103 views

Are there any security advantages to the “TrueCrypt-Paradigm”?

TrueCrypt and its successors use a file format that has the special property, that it looks completely random, there's only a salt (which is random) and the cipher text (which looks random). I like to ...
2
votes
1answer
197 views

Encrypting data before sending to SaaS tool and decrypting on browser view

I'd like to send data to a SaaS tool, where the data is stored in the cloud. I'll use Google Analytics as an example, but it applies to any similar service. Google Analytics does not allow you to ...
3
votes
5answers
590 views

Why can passwords be used to encrypt data, but are less strong for authentication?

Encryption software is often password based. Even if the adversary gets your computer they can't get the data without knowing the password, and bruteforcing is infeasible. Websites use passwords to ...
1
vote
0answers
6 views

If we should not reuse primes in DH, shouldn't we not reuse ECDH elliptic curve properties? [migrated]

An article How is NSA breaking so much crypto? describes NSA's methods for breaking encryption. If a client and server are speaking Diffie-Hellman, they first need to agree on a large prime number ...
79
votes
8answers
211k views

How to determine what type of encoding/encryption has been used?

Is there a way to find what type of encryption/encoding is being used? For example, I am testing a web application which stores the password in the database in an encrypted format ...
268
votes
3answers
269k views

What's the difference between SSL, TLS, and HTTPS?

I get confused with the terms in this area. What is SSL, TLS, and HTTPS? What are the differences between them?
14
votes
2answers
333 views

How does SHA3 (Keccak & SHAKE) compare to SHA2? Should I use non-SHAKE parameters?

Keccak is the winner of the SHA3 competition. Since Keccak is highly customizable (presumably for security/memory/time/speed tradeoffs) there does seem to be some controversy around how Keccak ...
9
votes
1answer
136 views

How to compare key management strategies

Are there formal security definitions or frameworks to evaluate the quality of a key management scheme? Can I state something like "the key is XYZ-protected against a polynomial adversary given that ...
15
votes
3answers
3k views

What should I know before configuring Perfect Forward Secrecy?

PFS has gained attention in our audit department because of its innate ability to limit our exposure if someone steals our private key. What pitfalls or common mistakes should I be aware of before ...
822
votes
23answers
162k views

XKCD #936: Short complex password, or long dictionary passphrase?

How accurate is this XKCD comic from August 10, 2011? I've always been an advocate of long rather than complex passwords, but most security people (at least the ones that I've talked to) are ...
45
votes
4answers
65k views

How to estimate the time needed to crack RSA encryption?

How to estimate the time needed to crack RSA encryption? I mean the time needed to crack Rsa encryption with key length of 1024, 2048, 3072, 4096, 5120, 6144, 5120, 7168, 8192, 9216, 10240, 11264, ...
2
votes
4answers
182 views

How could online encryption ever work? [duplicate]

I have recently read about the german enigma machine in WW2, It worked in a way that every day the machine configuration was sent per mail to the different operators. (I couldn't find official sources ...
19
votes
2answers
2k views

Homomorphic encryption used for e-voting?

I was reading wikipedia about homomorphic encryptions, and one part got me a bit confused: "The homomorphic property of various cryptosystems can be used to create secure voting systems, ..." ...